U.S. Sen. John McCain, who has been critical of United Launch Alliance in the past, has boosted his ire toward the Colorado rocket launcher to a new level in the wake of its refusal to bid on a Pentagon contract.

McCain, the Arizona Republican who chairs the Senate Armed Services Committee, said in a letter this week to U.S. Defense Secretary Ashton Carter that he wants Centennial-based ULA's accounting systems audited, Space News reports.

McCain, whom President Barack Obama defeated in the 2008 presidential election, also called for a report on whether ULA's decision to use its dwindling supply of Russian-made rocket engines on non-military launches was an attempt to "subvert" the will of Congress.

As the DBJ's Greg Avery has reported, ULA -- which has been the military's primary space-launch rocket contractor for years -- said last month it would not bid on a contract potentially worth billions of dollars to launch the first of a planned series of GPS III global positioning satellites for the Pentagon starting in 2018.

That decision left Elon Musk's SpaceX as the only eligible bidder. SpaceX -- also known as Space Exploration Technologies Corp. -- has only recently been certified as eligible to bid on such contracts, which previously were routinely awarded to ULA.

But a SpaceX rocket exploded in June and it has not launched a payload into space since, and "the Air Force would be hard-pressed to award SpaceX a GPS III contract while (its) Falcon 9 rockets are grounded," Avery reported. ULA, on the other hand, has logged more than 100 successful launches.

ULA, a joint venture of Lockheed Martin Corp. and the Boeing Co., cited Congress' cap on use of Russian-made engines on future military flights other than a handful still in the company's stockpile. Congress restricted imports of the RD-180 engines for U.S. military space missions as part of sanctions against Russia for its annexation of Crimea.

But ULA said it had designated its remaining RD-180 engines not already committed to Pentagon flights to non-military missions.

There was no immediate response from ULA to national reports of McCain's letter. But last month, Tory Bruno, ULA's CEO, said he hopes that ULA hopes to be able to compete for future launches in the nine-satellite series the Air Force plans to launch, and that Congress will relax limits on Russian rocket use.

In a letter last month to Senate Appropriations Committee Chairman Thad Cochran, R-Mississippi, McCain accused ULA of trying "to manufacture a crisis by prematurely diminishing its stockpile of (Russian) engines."